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Build up weld

04-04-2010, 05:41 PM

In my line of work I have opportunity to learn how to weld journals .Parts will come in that need repair and the the journals will need to welded and turned down to size.When they get welded there can be no pits on the finished diameter.I know you will get a laugh but all we have is a 140 Hobart mig for the job.The parts vary from a .5 in. to3.0 in . in diameter.The guy who regulary welds these parts gets it done flawlessly and I am trying to pick up the skill also.He does it with no preheat.A little more to the story we have a Miller 250 mig at my disposal and that is the machine I would like to use. What are some suggestions that would help? I do have for my use an induction coil for preheat . We normally use a circular pattern lapping over the previous weld in a upside down j.On bigger diameters I have experimented with a straight weld but that can sometimes bend the part. I know I am rambling a bit and I will try to post pictures for clarity. Thanks for all your help.

Vertical bores can be spiral welded from the bottom up using the 140 machine you have, if they are big enough in diameter you can do overlapping verticle weave passes. I always did the vertical passes opposing each other until they all overlapped. Horizontal bores can be welded with the same machine doing overlapping stringers. With the 140 you will probably be running it at it's duty cycle for buildup. Preheat helps keep the weld soft for the machining; damaging the tooling less, but isn't crucial on smaller parts, though I would recommend it anyway. I always used a rose bud and took the part up to at least 250F for solid wire buildup.

Buildup on the outside of a shaft is just the same, except I wouldn't do a verticlally fixed shaft buildup in spirals, unless it was in a positioner to rotate it constantly.